Adequate prenatal care and timely syphilis screening and treatment could have prevented 90% of CS cases, the report said.
The CS rate in Baltimore increased from 62 per 100,000 live-born infants in 1993 to 282 in 1996. The increase among blacks was from 113 in 1993 to 564 in 1996. During the study period, 90 women with active syphilis during pregnancy and who delivered infants were identified. Of these, 62 (69%) women delivered infants with illnesses meeting the CS case definition; 28 (31%) women who were adequately treated for syphilis during pregnancy delivered infants without CS.
All infants with CS were reported to BCHD. Of the 62 mothers of CS patients, four (7%) delivered stillborn infants. Both groups of mothers had similar demographic characteristics.
Of the 90 women, the mean age was 26 years; 86 (96%) were black and six (11%) of 56 mothers tested were HIV-positive. Fifty-four (60%) had either a positive toxicology screen or self-reported cocaine or heroin use during pregnancy; 24 (44%) of 54 had a record of substance-abuse treatment.
The prevalence of drug use was high among all women with syphilis during pregnancy. However, in this investigation, the type of drugs used differed between the two groups.
Of those women tested by toxicology screening at delivery, nine (23%) of 40 mothers of CS patients and 10 (53%) of 19 mothers of uninfected children were positive for cocaine (P<0.03); four (10%) of 40 mothers of CS patients and one (5%) of 19 mothers of uninfected children was positive for heroin, and 13 (33%) of 40 mothers of CS patients and one (5%) of 19 mothers of uninfected children (P<0.05) was positive for both drugs.
Heroin use, either alone or in addition to cocaine use, was significantly associated with CS, and cocaine use alone was not significantly associated with CS among this group of women. These results may not be generalizable to other populations.
Mothers of CS patients and mothers of uninfected children differed with respect to several prenatal care-related factors. Of the 58 mothers of CS patients, 43 (74%) had a third trimester diagnosis of syphilis compared with eight (29%) of 28 mothers of uninfected children (P<0.01). Records of CS patient mothers were more likely than records of mothers of unifected children to include documentation suggesting their pregnancy was unintended (37% vs. 14%; P<0.05). Among the 90 mothers, three were allergic to penicillin; none was desensitized and treated with penicillin during pregnancy. Therefore, the three mothers delivered infants who had illnesses meeting the CS case definition.
Treatment of maternal syphilis with penicillin is highly effective in preventing CS. However, infants born to inadequately treated mothers can require parenteral therapy at an estimated cost of more than $12,000 per infant.
Thirty-six (58%) mothers of CS patients had no prenatal care or initiated prenatal care late in the third trimester. Missed prevention opportunities were identified for most of the mothers of CS patients who had early prenatal care. At the time of this investigation, Maryland law required syphilis screening of all pregnant women in the first and third trimesters, but there was no stipulation on the timing of the third trimester test.
Of the 54 CS patients whose mothers had entered prenatal care by 28 weeks' gestation, syphilis screening and treatment at 28 weeks' gestation and other routine serological testing could have prevented 18 (29%) of the 62 cases. An additional six (10%) CS patients were infected too late in pregnancy to prevent CS, including two who seroconverted after delivery.
The CS epidemic in Baltimore occurred despite dramatic declines in syphilis incidence in the United States. Nationally, CS declined 72% from a peak of 107 cases per 100,000 live-born infants in 1991 to 30 in 1996; in Baltimore, the rate was nearly 10-fold higher in 1996 than the national rate. Among blacks, the national rate was 128 per 100,000 live-born infants in 1996 compared with 564 in Baltimore.
The large racial differential in CS rates suggests that other factors for which race is often a proxy (e.g., differential access to and quality of health care services) may be contributing to this epidemic and differentially affecting blacks.
The findings in this report are subject to at least two limitations. First, most of the data were gathered through record review. As a result, key variables (e.g., unintended pregnancy and detention history) may be underreported. Second, because spontaneous abortions were not included, stillborn infants may be underestimated.
Despite these limitations, the finding that lack of adequate prenatal care was associated with CS is consistent with other studies.
Although reducing the risk for CS will ultimately depend on control of adult syphilis, prevention specific to pregnant women with active syphilis is feasible. In response to this epidemic, BCHD has alerted prenatal care providers and worked with other health care service providers to initiate screening and treatment programs for women of reproductive age.
Through collaborative efforts of DHMH, BCHD, the Maryland Department of Public Safety and Correctional Services, and CDC, a rapid screening and treatment program for detainees and female arrestees was initiated at the Baltimore Central Booking Intake Center. Such interventions have been successful in other settings. STD clinical services have been strengthened at public STD clinics, including additional clinicians and other staff.
In addition, the Maryland regulation on syphilis testing during pregnancy was amended in January to require a third trimester screening test at 28 weeks' gestation or the first visit thereafter to ensure diagnosis in time to prevent perinatal transmission. Syphilis screening at delivery has also been mandated.
For your information:
- CDC. Sexually transmitted disease surveillance, 1997. Atlanta, Georgia: US Department of Health and Human Services, Public Health Service, CDC, 1998.
- CDC. Outbreak of primary and secondary syphilis-Baltimore City, Maryland, 1995. MMWR 1996;45:166-9.
- CDC. Case definitions for infectious conditions under public health surveillance. MMWR 1997;46(no. RR-10).